Acoustic horn and method of and apparatus for making the same



ACOUSTIC HORN AND METHOD OF AND APPARATUS FOR MAKING THE SAME Nov. 12, 1929. J. MCW. STONE 4 Sheeias-Sheet 1 Filed Sept. 22, 1927 00 d 0000 0 0 00000.. 4 oo o o o o o Nov. 12, 1929. J. MQW. STONE 1,735,476

ACOUSTIC HORN AND METHOD OF AND APPARATUS FOR'MAKING THE SAME Filed Sept; 22, 192'! 4 Sheets-Sheet 2 I LU I J 1929. J. M W. STONE 1,735,476

ACOUSTIC HORN AND METHOD OF AND APPARATUS FOR MAKING THE SAME Nov. 12,

4 Sheets-Sheet '3 Filed se a. 22, 192'! Nov. 12, 1929. J. M W. STONE 73 ACOUSTIC HORN AND METHOD OF AND APPARATUS FOR MAKING THE SAME Filed Sept. 22, 1927 4 Sheets-Sheet 4 Zz'ams 05%276 Q' 9% Patented Nov. 12, 1929 UNITED {STATES PATENT OFFICE JOHN MCWILLIAMS STONE, OF CHICAGO, ILLINOIS, ASSIGNOR TO. OPERADIO MANU- FACTUBINGCQ, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS-- ACOUSTIC HORN AND METHOD OF AND APPARATUS FOR MAKING THE SAME Application filed September 22, 1927. Serial No. 221,292.

This invention relates to an acoustic horn and method of-and apparatus for making I same.

' The invention is fully described in the following specification and shown in the accompanying drawings, in which:

Figure 1 is a front elevation of the completed horn;

Fig. 2 is a side elevation of the same; Fig. -3 is a front elevation showing the grille-work front removed;

Fig. 4 is a partial enlarged section on the line 4 of Fig. 1;

Fig. 5 is a partial section of the lower part of the horn taken on the line 5 of Fig. 2;

Fig. 6 is a top plan view of the clamp and mold for making the horn; Fig. 7 is a partial plan view of the same showmg the clamp open and the top removed; 7

Fig. 8 is a side elevation of the same; Fig. 9 is a section on the line 9 of Fig. 13; Fig. 10 is a partial enlarged section on the line 10 of Fig. 12, showing the small end of the horn with threaded th'imble;

Fig. 11 is a partial section on the line 11 of Fig. 12 showing the large end of the horn; Fig. 12 is a top plan view of the bottom of .the mold with the cylinder housing in place thereon; and x Fi 13 is a-similar'view of the same showing t e flexible corein place ready for pour- Triefl this horn is-made by taking a cylindrica sheet metal drum A (Fig. 7), placing it in a clam B which when closed forces it into an elliptical desired form after which a bottom 0 (Fig. 9) is forced over the edge of the drum, the whole being held in place by gravity and by friction. A flexible mold D, (Fig. 13,) of gelatin, rubber or the like, is then placed against the drum A and coiled somewhat as shown, the overlapping portions of the coil being separated by any suitable form of spacer. The form is then filled with a suitable mixture of freshly prepared gypsum and water or the lilie which then uickly sets or hardens so t at the fiexib y tapered coil D may be withdrawn and the bottom C removed leaving the horn cast in gypsum within the cylinder A.

The clamp B consists essentially of two semi-elliptical sections 10'and 11 which terminate in laterally extending ears 12 and 13 respectively. A U-shaped member 14; is secured to each of the cars 12 and has slots 15 through which pass pins 16 which are carried by the ears 13. The ears 13 also carry pins 17 which extend through corresponding holes in the cars 12 so as to guide the two halves of the clamp. An eccentric can. lever 18 is pivotally carried on the bolt 19 which extends through the U-shaped member 14 and bears upon the ear 13. When the cam levers 18 are drawn outwardly they permit the clamp sections 10-and 11 to be separated as shown in Fig. 7. Drawing the cam levers 18 as shown in Fig. 6, forces the two clamp sections together.

The cylinder A is made in circular form as-shown in, Fig. 7 and may have a series :of beads as shown in Fig. 2. This cylinder,

which is preferably of sheet metal or the like, 1s placed between the two clamp sections 10 and 11 after which the clamps 18 are turned so as to cause the clamps to close forcing the cylinder A from the circular into the elliptical form. It will be understood however that it maybe pressed into other shapes if desired.

The clamp section 10 .has an arm. 20 secured thereto, the outer end of this arm having a ball 21 formed thereon which is mounted in a spherical socket 22 which in-turn is secured to the table 23 upon which the clamp rests.

' The clamp section 11 carries a-handle24 by which-it maybe turned. This handle has feet 25 extending in opppsite directions and of a height which will eep the clamp substantiallyhorizontal when either of the feetrest upon the table 23.

With. he clamp sections 10 and 11 secured about a cylinder A, the bottom of the cylinder is closed fits ti htly around the bottom of the cylinder A as s own in Fig. 9 and has legs 26 whereby it rests uponthe table-top 23.

The bottom mold C has a lining of gelatin, rubber or the like 27 which is so formed as to shape the front or bell of the horn and has an abrupt surface 27? (Fig. 12) adapted to receive the large end 'of. the core D. Lugs 28 extend from the surface 27 and have a slot 29 adapted to receive a ring or eyelet 30 which is carried by the core D.

This core preferabl has-a lead center 31 into which the eyelet 30 is secured, this center being surrounded by a coating 32 of gelatin, rubber or the like. If desired, the entire core may be made of gelatin, the use of which is well known in the art of making statuettes or the like. 'Wher, however, a core having a center 31 of lead or the like is used, the core is self-supporting and therefore does not require chaplets, separators or the. like to separate the overlapping portions of the core.

The core is then coiled within the cylinder as shown in Fig. 13, sufi'lci'ent space being left which is used for filling the horn or they may" between the outer portion of the core D and the shell .to insure a sufliciently. thick wall. If desired, rings or chaplets 33 are placed around. the core or any other means may be used t'o'insure a proper spacing for thefilling material for the core itself. These chaplets may be made of the same material as that p be madeof a spiral-sprlng as shown at 34.

The small end of the core is then led into a thimble 35 which has previously been placed within the bottom mold C and secured in place by means of a screw 36 extending therethrough from the bottom. The small end of the core D is thus firmly anchored.

Ifdesired, a mold top 37 maybe fitted over the'shell A, top carrying a gelatin form 38 I mold top.

which is secured thereto by means-of lugs 39' extending through suitable openings in the A A mouth 40 is provided whereby the material for filling the horn. may be poured. I j

This material, consisting largely of plaster of Paris with a suitable coloring matter, is mixed with water after which it is poured .into the mold, the operator striking the mold so as to cause the material to flow to all parts of the mold. This is then allowed to stand until it is hard enou h to permit the mold to be removed. It is t screw has-been withdrawn, thereby-exposing the large end of the core D. Some ofthe. have gotten in between pouring material ma the face 27 and the arge endof the core D,

en turned upside downand the bottom mold O removed after the withdrawn. This can be assisted by pressing any suitable instrument through the sleeve 35 against the small end of the core D.

y means of a bottom mold C which.

' a horn and one which provides a horn whic is "self-contained.

The horn thus made may be decorated in any desired manner as by painting or laquering and may be placed upon any suitable-support. The horn when thus made still contains a considerable quantity of moistureand this may be driven out by heating it in a suit- 5- able drying room while hot air is caused to passoverit. I

In the operation of placing the shell in the clamp in the first instance, nuts 41 are placed within the shell and are. held by means of suitable bolts 42 in one of the clamp sections. 1 These nuts are then cast in the horn and are retained so that a base 43 (Fig. 3) maybe secured to the shell by means of. bolts 44 which are screwed into the nuts 41. 1 5 A suitable .front 45 may be then secured K in place by snapping it over the edge of-the shell and this carries a suitable'screen 46.

Clamps 47 or the like'may be used to hold, the mold bottom 0 and the top mold 37 'on 1 0 the drum A. When the bottom mold C is used alone, these clam s are not used, the-weight of the whole restingupon the ower mold 0. While I have shownand described but a single embodiment of this invention, it is to be understood thatit is ca able of many modifications. Changes-there ore-in the construe-- tion and arran ement may be-made which do not depart rom the spirit andscope of the invention as disclosed 1n"- the appended no This shape, however, is not always the final 1 desired shape for the vhorn. By. putting it in f the form or. clamp B, it is forced into any desired shape. For example, as shown, it is distorted into an elliptical shape or form.

The. drum is then filled with gypsum or plas- 12o ter, as above described, and this plaster hardens or sets.v This hardeningor setting of theplaster then serves to vpermanentl hold the drum A in thedesir'ed' shape; an the drum 7 :will retain its shape even after. the clamp B is removed.

Iclaim: I K The method ofmaking a loudspeaker horn including; forming an open ended drum of sheet metal; deforming said. out of its .130

cylindrical shape by suitable shaping means and temporarily holding said drum in said deformed shape by said shaping means; casting a loud speaker horn in said drum, allowin porarlly holding the drum in its deformed shape; and removing the shaping means, permitting the drum to remain on the casting as a part of the loud speaker horn. and permanently held in its deformed shape by said casting. v

In testimony whereof I have hereunto set my hand this 15th day of September, 1927.

JOHN MOWILLIAMS STONE.

the same to harden while so tem-' 

